基于CBCT实时三维可视化透视导航技术关键科学基础和方法的研究

Recently many image-guided Interventional techniques have been well developed and increasely accepted in medical practice, 3 dimensional image guidance is obviously prefered to 2D guidance during these interventional procedures. Computer and software assisted guidance navigation technique greatly improved the accuracy and safety of intervention treatment based on 3D data set, was shown promising in this prosperously developing era of computer digital technology. Compared with the international advanced level, the research development of computer assisted navigation technique was left behind for many years in China. Cone beam CT （CBCT）is a new emerging technology that allows 3D image acquisition via a C-arm fluoroscopy system which is now available in many Chinese medical center. 3D fluoroscopy guidance using cone beam CT with dedicated needle path planning software is a promising new interventional technique, but is not widely accepted for its many shortages, such as the low denstiy resolution of CBCT, difficulty of target area segmentation, low visulization of target area on fused 3D image, much influence of respiratory movement,and other key techniques. the purpose of this study was to develop a software assisted Real-time 3D visualized Fluoroscopy Navigation Guidance system merging cone beam CT with planning softwares which are dedicated to optimize the 3D image segmentation and analysis, 3D colour staining techniques and volume rendering (VR), respiratory register, fluoroscopy coregistered with a 3D data set and needle path-planning. this newly developed system is going to firstly solve the key techniques in the world and realize the real 3D visualized fluoroscopy navigation based on CBCT which would effectively improve the accuracy and safety of interventional percutaneous needle punture than before, no matter for the puncture of target tumor or ductal structure.

近年来影像引导介入治疗技术迅速兴起，介入技术的三维影像引导成为趋势，计算机辅助下的三维影像导航技术成为该领域数字信息化时代的鲜明特征，使介入治疗准确性和安全性明显提高。随着具有CBCT三维成像功能大型平板数字血管机已经进入中国临床，基于CBCT三维引导穿刺技术呈现良好的应用前景，但其计算机辅助的导航技术的研发尚存在瓶颈，由于CBCT密度分辨率低，靶区分割困难，融合图像的三维可视性差、呼吸动度影响等，使其难于直接用于临床中三维引导穿刺。本课题将研究CBCT优化对比显示方法、CBCT三维组织器官分割算法、三维彩色半透明绘制技术、呼吸校正技术，在此基础上结合三维穿刺计划、图像融合、参数关联等技术，突破各个关键技术难点，形成临床适用的处理算法和三维引导，并达到良好的精度，实现真正意义的实时三维可视化透视穿刺导航，满足对复杂器官内部肿瘤靶区和管腔组织的三维可视化穿刺，显著提高穿刺的准确性和安全性。

三维可视化引导穿刺诊断和治疗技术是介入放射学的前沿和热点领域，本研究是基于对Cone Beam CT实时三维可视化显示技术的研究，我们围绕该技术进行了一系列关键问题的探索。包括：CBCT的优化显示技术，通过临床双期CBCTHA、碘油CT、增强螺旋CT或MR观察双期CBCTHA对于肝内小于30mm的肿瘤结节的显示优越性。探索CBCT三维体数据中目标靶区提取的方法：膈肌、靶区、血管和骨骼。实现了主动轮廓模型方法（active contour）对膈肌的分割，保证了膈肌轮廓的连续性和平滑性。对肿瘤、囊肿、胆囊等靶区使用水平集(Levelset) 的方法进行分割，使其不受轮廓拓扑结构变化的影响。血管的分割使用多尺度的血管增强滤波的方法，从而提取肝脏内的重要血管。骨骼的分割使用阈值的方法，很好地分割出骨骼结构作为配准验证的基础。实现了CBCT三维体数据的重投影算法，解决了在投影角度、检测床的位置或源到探测器的距离发生变化时，三维体数据与二维透视图像进行准确匹配和关联的完整算法，并进行了模具、患者体内手术银夹和栓塞后肿瘤的匹配关联的测试验证，目标物位移最小值的平均值为1.15mm，可以满足临床穿刺中5mm安全区域的需要。